I have a table say, ITEM, in MySQL that stores data as follows:
ID FEATURES -------------------- 1 AB,CD,EF,XY 2 PQ,AC,A3,B3 3 AB,CDE 4 AB1,BC3 --------------------
As an input, I will get a CSV string, something like “AB,PQ”. I want to get the records that contain AB or PQ. I realized that we’ve to write a MySQL function to achieve this. So, if we have this magical function MATCH_ANY defined in MySQL that does this, I would then simply execute an SQL as follows:
select * from ITEM where MATCH_ANY(FEAURES, "AB,PQ") = 0
The above query would return the records 1, 2 and 3.
But I’m running into all sorts of problems while implementing this function as I realized that MySQL doesn’t support arrays and there’s no simple way to split strings based on a delimiter.
Remodeling the table is the last option for me as it involves lot of issues.
I might also want to execute queries containing multiple MATCH_ANY functions such as:
select * from ITEM where MATCH_ANY(FEATURES, "AB,PQ") = 0 and MATCH_ANY(FEATURES, "CDE")
In the above case, we would get an intersection of records (1, 2, 3) and (3) which would be just 3.
Any help is deeply appreciated.
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First of all, the database should of course not contain comma separated values, but you are hopefully aware of this already. If the table was normalised, you could easily get the items using a query like:
select distinct i.Itemid from Item i inner join ItemFeature f on f.ItemId = i.ItemId where f.Feature in ('AB', 'PQ')
You can match the strings in the comma separated values, but it’s not very efficient:
select Id from Item where instr(concat(',', Features, ','), ',AB,') <> 0 or instr(concat(',', Features, ','), ',PQ,') <> 0
For all you REGEXP lovers out there, I thought I would add this as a solution:
SELECT * FROM ITEM WHERE FEATURES REGEXP '[[:<:]]AB|PQ[[:>:]]';
and for case sensitivity:
SELECT * FROM ITEM WHERE FEATURES REGEXP BINARY '[[:<:]]AB|PQ[[:>:]]';
For the second query:
SELECT * FROM ITEM WHERE FEATURES REGEXP '[[:<:]]AB|PQ[[:>:]]' AND FEATURES REGEXP '[[:<:]]CDE[[:>:]];
select * from ITEM where where CONCAT(',',FEAURES,',') LIKE '%,AB,%' or CONCAT(',',FEAURES,',') LIKE '%,PQ,%'
or create a custom function to do your MATCH_ANY
Alternatively, consider using RLIKE()
select * from ITEM where ','+FEATURES+',' RLIKE ',AB,|,PQ,';
Just a thought:
Does it have to be done in SQL? This is the kind of thing you might normally expect to write in PHP or Python or whatever language you’re using to interface with the database.
This approach means you can build your query string using whatever complex logic you need and then just submit a vanilla SQL query, rather than trying to build a procedure in SQL.